Kernel 3.15.0-rc2, btrfs-progs 3.14.1 While doing some minor package updates my btrfs root partition [*] decided to corrupt itself. There was no system crash, although I had plenty of these (due to an USB-related regression) in recent weeks that resulted in no trouble. First only one of a package's folders was corrupted, any access to files within (incl. attempts to delete) printed btrfs: corrupt leaf, slot offset bad: block=842924032,root=1, slot=88 to dmesg (I'm actually not sure about the numbers, but that was indeed the error message). After moving the folder out of the way the partition continued to appear working as normal, one reboot also worked fine. Now I can't boot at all (beyond loading the kernel image located on another partition). Attempting to mount the partition on a ArchLinux's current Live-CD (kernel 3.13.7) prints btrfs: device label Linux devid 1 transid 55586 /dev/sdc5 btrfs: use ssd allocation scheme btrfs: disk space caching is enabled btrfs: checking UUID tree btrfs: corrupt leaf, slot offset bad: block=842924032,root=1, slot=88 btrfs: corrupt leaf, slot offset bad: block=842924032,root=1, slot=88 BTRFS error (device sdc5): Error removing orphan entry, stopping orphan cleanup BTRFS critical (device sdc5): could not do orphan cleanup -22 Doing "btrfs check /dev/sdc5" merely first prints ten free space inode generation (0) did not match free space cache generation ([different transids between 40010 and 55578]) to then abort with checking fs roots btrfs: cmds-check.c:1151: procecss_file_extent: Assertion `!(rec->ino != key->objectid || rec->refs > 1)' failed. I'm reluctant to try any of "btrfs check" options since the last three times I did this (with other partitions) it resulted in the partition becoming entirely trashed, while before at least "btrfs restore" still managed to extract some data each time. [*] Organised following http://blog.fabio.mancinelli.me/2012/12/28/Arch_Linux_on_BTRFS.html
NB: The affected folder was one within /usr/include/qt4 (which I then moved to /usr/BROKEN, to successfully reinstall the package), ie. on the __current/ROOT subvolume. Which seems the only subvolume affected (yet). Mounting & accessing the other three (__current/{var,home,opt}) still works.
Alright, turns out the partition does actually mount on 3.15-rc2 (error messages remain, of course). But systemd will fail to continue booting as /bin/mount returns "exit status 32" and / thus ends as ro, yet can be manually remounted as rw. Another error message I've spotted with 3.15 is BTRFS error (device sdc5): error loading props for ino 1810424 (root 257): -5 I've now tried to mount with -o recovery and clear_cache, no effect.